Non-cardiac chest pain (NCCP), defined as intermittent chest pain in which clinical investigation fails to identify any structural or biochemical etiology, affects over 180,000 new patients per year. The etiology of NCCP remains unclear though the esophagus has been implicated in up to one third of patients with anginal chest pain, but a normal cardiac catheterization. Traditional thinking has focused on the role of motility abnormalities, gastroesophageal reflux disease, and psychosocial factors. More recently, investigators have suggested that "visceral hypersensitivity" may be an important factor. Patients with NCCP have been found to experience pain at lower levels of esophageal balloon distention than healthy controls. Positron emission tomography allows the functional mapping of cortical activation which occurs in response to various stimuli. PET scanning has recently been applied to the investigaton of the functional bowel diseases.